Bacteriologists are not in a position to disregard the limitations recognised by the physiologists. Precise data which are not available from experiments are far from sufficient to explain the properties of living matter; they must be supplemented by vaguer conceptions about the functions of a cell, its internal organisation and its susceptibility to stimulative or inhibitory agencies—conceptions which cannot yet be translated into recognised chemical substances and physical properties. One must therefore start by recognising that bacterial virulence, being dependent on vital processes, cannot be fully explained in chemico-physical terms.

1. There is recorded for the first time an outbreak of milk-borne bacillary dysentery which has been proved to be due to B. dysenteriae Sonne.

2. In this milk-borne outbreak of Sonne dysentery there were over 150 cases and no deaths, the absence of mortality being in marked contrast to the high mortality rate which accompanies milk-borne outbreaks of Flexner dysentery.

3. Several milk-borne outbreaks of enteritis simulating dysenteric infections have been recorded in which the evidence has pointed to a living bacillus of unrecognised type as the causal agent. It is obvious that in future B. dysenteriae Sonne will require to be excluded from the group of the unrecognised viruses.

(1) Non-specific agglutination as tested by thermo-agglutination, peptone agglutination, lactic acid agglutination and Michaelis' acid agglutination falied in the primary object of differentiating between Br. melitensis and Br. abortus.

(2) Thermo-agglutination was only observed in strains of Br. paramelitensis.

(3) With peptone agglutination no strain gave a positive result.

(4) The results of lactic acid agglutination and Michaelis' acid agglutination ran practically parallel. No distinction could be observed between Br. melitensis and Br. abortus. Strains of both of remote origin gave slight agglutination with lactic acid while recently isolated strains of Br. abortus were negative. Very definite agglutination, however, was observed by both methods with paramelitensis and paraabortus strains, but no differentiation was possible between such strains.

(a) The slow lactose fermenting bacilli which we have investigated cause an acute febrile illness in man. The general symptoms may be so severe that the diagnosis of typhoid and paratyphoid fever has been made. Such cases are invariably due to an acute infection of the urinary tract, more specially acute pyelitis or pyelo-nephritis, but the general symptoms may be so severe at the onset of the illness that the urinary manifestations are masked.

(b) Three fatal cases have occurred.

(c) In cases of acute diarrhoea, with or without blood and mucus, these bacilli may be present in pure culture in the faeces.

(d) Chronic urinary infections due to these bacilli are uncommon.

(e) The bacillus of so-called columbensis fever is allied to these bacilli.

In the year 1911 the heading “Status Lymphaticus” was first used in the publications of the Registrar-General of England and Wales and, in that year, 121 deaths were assigned primarily to this heading; Status Lymphaticus was also mentioned in the certificates relating to 25 of the deaths which occurred under anaesthesia. The heading was retained in the published tabulations as first introduced until 1921, when certifications of Status Lymphaticus were classified under the heading of “Diseases of the Thymus,” of which statistical group they have, so far, formed the whole. Between 1911 and 1924 (inclusive) the annual deaths—inclusive of those associated with anaesthesia—have fluctuated between 145 and 273. In the last four years there has been little variation, 209 in 1921, 204 in 1922, 200 in 1923 and 199 in 1924. Most of the deaths are in the age group 0–5 and a considerable majority are of males. Thus in the last two available years, 1923 and 1924, of 399 deaths 289 were at ages 0–5 and 258 were of males (respectively 72 and 65 per cent.). If the 85 deaths in which anaesthesia was an associated condition are excluded, 81 per cent. are of children aged 0–5 and 64 per cent. of males (Table I).

1. Scarlatinal streptococci obtained from the throats of cases of scarlet fever can be divided into various groups by means of agglutination and absorption tests. The same type of streptococcus can on occasion originate at least five separate clinically distinguishable diseases, namely, scarlet fever, tonsilitis, erysipelas, puerperal fever, and broncho-pneumonia, and it would appear that, so far as streptococcic infections are concerned, the nature of the disease entity is determined by the toxigenic qualities of the type of streptococcus, by the susceptibility or insusceptibility of the individual as determined by the absence or presence of the specific antibodies in the blood, and by the site of the infection itself (see p. 330).

2. Strong corroboration for the view that the S. scarlatinae is the causal organism of scarlet fever is obtained from the following findings, viz.:

(a) S. scarlatinae have been isolated from the throat brushings of practically all acutely ill scarlet fever patients (see p. 329).

(b) The whole clinical picture of scarlet fever going on to marked desquamation is produced by the subcutaneous injection of the exotoxin derived from the S. scarlatinae, the exotoxin having been haeated to 55° C. for one hour, with a view to destroying any filterable living virus which might be associated with the filtered exotoxin (see p. 342).

(c) In the Schultz-Charlton reaction the blanching of the scarlet fever rash is caused by the serum of a horse immunised against S. scarlatinae and its toxins.

(d) Dick-positive and Dick-negative reactions as produced by the intradermal injection of the streptococcus toxin have the closet correspondence to the degree of susceptibility or immunity to scarlet fever of the respective reactors (see p. 334).

(e) Susceptible nurses once they are actively immunised by injections of scarlatinal streptococcus toxin have been shown to be immune to the toxin of scarlet fever (see p. 337), and susceptible school children similarly inoculated are likewise immune (see p. 338).

(f) Return cases of scarlet fever can be prevented by actively immunising susceptible contacts with scarlatinal streptococcus toxin prior to the scarlet fever patient being discharged from hospital (see p. 339).

(g) Susceptible contacts can be safeguarded from taking scarlet fever by passively immunising them with a sufficient does of antistreptococcus serum obtained from a horse wich has been immunised by injections of S. scarlatinae and its toxin (see p. 349).

3. The limitations of the Schultz-Charlton reaction as an aid in the diagnosis of scarlet fever have been confirmed (see p. 330).

4. Evidence has been obtained which firmly establishes the value of the Dick suseptibility test as a measure of susceptibility to scarlet fever (see p. 332).

5. Extensive corroboration of the value of the Schick test as a measure of susceptibility to diphtheria has been obtained (see p. 334).

6. The efficacy of active immunisation against scarlet fever by means of scarlatinal streptococcus toxin injections has been demonstrated by the fact that, while scarlet fever has been present in epidemic form in Aberdeen, no nurses or maids in Aberdeen City Hospital have contracted scarlet fever since June 1st, 1925, from which date the nursing and domestic staffs of the hospital have been actively immunised before being admitted for duty to the scarlet fever wards; whereas, prior to that date, an average of 8·5 nurses, or 9·5 per cent. of the nursing staff, and 1·4 maids, or 4·2 per cent. of the domestic staff. annually suffered from scarlet fever (see p. 337).

7. Coincident with the disappearance of scarlet fever in the immunised nursing staff of the City Hospital, there has been a notable increase in the incidence of streptococcic tonsilitis in these immunised nurses, and the streptococci obtained from these cases of tonsilitis in nurses commonly fall into one or other of the serological groups of scarlatinal streptococci; and accordingly it would appear to be proved that immunised nurses, while protected by immunisation from the toxic effects of the exotoxin of S. scarlatinae, are not protected against tonsilitis due to S. scarlatinae (see p. 338).

1. A collection was made of organisms of the coli-aerogenes group; 100 from the human intestine, 50 from animals, and 50 from the soil. To these were applied the indol test, the methyl red and Voges-Proskauer tests, and Koser' citrate test. The citrate test was also applied to certain non-lactose fermenters.

2. 89·4 per cent. of 150 faecal organisms gave the combination of a failure to grow in citrate solution, the production of indol, an acid reaction with methyl red and a negative Voges-Proskauer reaction.

3. There is a probability that some faecal organisms have crept into the “soil” series, but the contamination is not heavy enough to make the results useless. The figures show that the citrate and indol test are both useful, the citrate being a little better. The methyl red and Voges-Proskauer reactions were not helpful.

4. In the bacteriological examination of water in Shanghai it is safe to take those organisms which can grow in citrate but do not produce indol as being non-faecal.